Test results

Testbed configuration

CPU: AMD Phenom 9750 (Socket AM2+), 2.4 GHz (200x12), B3 stepping

Chipset: AMD 790FX

Motherboard: ASUS M3A32-MVP Deluxe, BIOS v.1201

OS: Windows XP SP2 x64.

We used the most logical SPD mode, recommended by the manufacturer, as the nominal mode (DDR2-800, 5-5-5-18). Tests were run in two modes of the Phenom memory controller: ganged (higher performance in single-thread access mode) and unganged (preferable for multi-threaded applications that actively access memory). We also evaluated overclocking potential of these modules, even though we couldn't really expect special talents from high-capacity memory modules here.

Qimonda DDR2-800 2x4096MB(HYS64T512020EU-25F-A)

Apacer Giant DDR2-1066 2x2048MB

Memory controller mode

Ganged

Unganged

Ganged

Unganged

Ganged

Unganged

Memory clock rate, MHz(DDR2 MHz)

400(800)

400(800)

456(912)

460(920)

400(800)

400(800)

Core clock rate, MHz(DDR2 MHz)

2400 (200x12)

2400 (200x12)

2736 (228x12)

2760 (230x12)

2400 (200x12)

2400 (200x12)

Memory controller clock rate, MHz(DDR2 MHz)

2000 (200x10)

2000 (200x10)

2280 (228x10)

2300 (230x10)

2000 (200x10)

2000 (200x10)

Default memory timings, voltage

5-5-5-18-2T,1.8 V

5-5-5-18-2T,1.8 V

5-5-5-15-2T,2.3 V

5-5-5-18-2T,2.3 V

5-5-5-15-2T,1.8 V

5-5-5-15-2T,1.8 V

Min. stable voltage

(not tested)

(not tested)

2.26 V

2.22 V

(not tested)

(not tested)

Avg. read bandwidth (MB/sec),1 core

6082

5535

6938

6354

6195

5760

Avg. write bandwidth (MB/sec),1 core

3469

3459

3960

3979

3548

3588

Max. read bandwidth (MB/sec),1 core

7014

6366

8000

7306

7149

6619

Max. write bandwidth (MB/sec),1 core

4888

4953

5575

5700

4965

4983

Avg. read bandwidth (MB/sec),4 cores

10764

10715

12270

12406

10960

11078

Avg. write bandwidth (MB/sec),4 cores

3506

4965

4000

5730

3550

5104

Max. read bandwidth (w/PF, MB/sec),4 cores

11047

10749

12594

12454

11238

11105

Max. write bandwidth (NT, MB/sec),4 cores

6288

5604

7168

7228

6315

6315

Min. pseudo-random access latency, ns

36.4

38.8

32.0

33.9

35.7

37.0

Min. random access latency*, ns

90.1

93.3

79.0

81.1

88.2

89.5

Block size: 32 MB

In our tests we also used a memory kit of lower capacity (2 x 2048 MB) from Apacer as a reference. You can see that performance differences at the same frequency (DDR2-800) are minimal. If you take a closer look, you can see that Qimonda modules suffer from a tad deeper writing performance slump in unganged mode, that's all.

Although these modules are apparently not targeted at overclockers (they do not come with heat spreaders and do not offer recommended modes with increased frequencies and voltage), they can still be overclocked. Their overclocking can make up for performance differences with memory modules of lower capacity (operating at the nominal frequency, of course) over and above.

Curiously enough, when overclocked, our modules under review demonstrate stable operation at a higher frequency in unganged mode, while their voltage is reduced from 2.3 V (it's a tacit maximum point, prolonged operation at higher voltages may shorten the service life of memory modules) to 2.2 V.

Conclusions

4GB DDR2 memory modules are not exotic anymore, their prices have dropped from the sky-high level. Workstation modules with ECC support are still the most widespread products in this category, but you can also get this much memory for your desktop as well. At least performance and reliability of the tested Qimonda modules meet the challenge, so you won't have to sacrifice either of those.